Initial studies in this grant proposal will characterize the intracellular and cell surface events taking place in the unusual in vitro regulation of expression of the insulin receptor on the Swarm rat chondrosarcoma chondrocyte, previously reported by this investigator. Employing heavy isotope amino acids, metabolic blocking agents, and quantitative radioligand binding to whole cells and detergent extracted cells, investigations will determine whether insulin inhibits synthesis of its receptor, stimulates translocation of the receptor, inhibits degradation of its receptor, or induces a change in the receptor's affinty. In vitro and in vivo experiments will be carried out investigating the interrelationship between circulating hormone levels, receptor number, cell growth, cell function, and differentiation of this tumor cell. Fetal rat monocytes-macrophages will be isolated, and the regulation of the insulin and insulin-like growth factor II receptors investigated, in order to determine whether the unusual regulation of the insulin receptor of this fetal-like tumor cell is a function of cell differentiation, and therefore is manifested by normal fetal cells. A limited number of human chondrosarcomas will be obtained and studied, in order to determine if the findings from the rat tumor are relevant to the analogous human disorder. The insulin receptor will be purified from the tumor using gel filtration chromatography and affinity chromatography employing monoclonal antibodies and immobilized insulin. Particular emphasis will be placed on the elucidation of the structure and function of the receptor's oligosaccharides using HPLC purification techniques followed by 500 MHz 1H-NMR analysis. The possible role of oxidative metabolites of arachidonic acid in generation of the insulin second messenger and in exocytosis of proteoglycans will be investigated. The major oxidative products of arachidonic acid produced by the cultured chondrocyte will be determined first. The effect of different HETEs, leukotrienes, prostaglandins, and inhibitors of the arachidonic acid pathways will then be studied.